Module:Util

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This is a meta module.

This module is meant to be used only by other modules. It should not be invoked in wikitext.

This module depends on the following other modules:

• Module:Arguments
• Module:Cargo
• Module:Util/config

Overview

Provides utility functions for programming modules.

Structure

Group	Description
util.cast	utilities for casting values (i.e. from arguments)
util.html	shorthand functions for creating some html tags
util.misc	miscellaneous functions

Usage

This module should be loaded with require().

The above documentation is transcluded from Module:Util/doc. (edit | history)
Editors can experiment in this module's sandbox (create | mirror) and testcases (create) pages.
Subpages of this module.

-------------------------------------------------------------------------------
-- 
--                              Module:Util
-- 
-- This meta module contains a number of utility functions
-------------------------------------------------------------------------------

local getArgs -- Lazy load require('Module:Arguments').getArgs
local m_cargo -- Lazy load require('Module:Cargo')

-- The cfg table contains all localisable strings and configuration, to make it
-- easier to port this module to another wiki.
local cfg = mw.loadData('Module:Util/config')

local i18n = cfg.i18n

local util = {}

-- ----------------------------------------------------------------------------
-- util.cast
-- ----------------------------------------------------------------------------

util.cast = {}

function util.cast.text(value, args)
    -- Takes an arbitary value and converts it to text.
    -- 
    -- Also strips any categories
    --
    -- args
    --  cast_nil      - Cast lua nil value to "nil" string
    --                  Default: false
    --  discard_empty - if the string is empty, return nil rather then empty string
    --                  Default: true
    args = args or {}
    if args.discard_empty == nil then
        args.discard_empty = true
    end
    
    if value == nil and not args.cast_nil then
        return 
    end
    
    value = tostring(value)
    if value == '' and args.discard_empty then
        return
    end
    
    -- Reassign to variable before returning since string.gsub returns two values
    value = string.gsub(value, '%[%[Category:[%w_ ]+%]%]', '')
    return value
end

function util.cast.boolean(value, args)
    -- Takes an arbitrary value and attempts to convert it to a boolean.
    --
    -- for strings false will be according to i18n.bool_false
    --
    -- args
    --  cast_nil  if set to false, it will not cast nil values
    args = args or {}
    local t = type(value)
    if t == 'nil' then
        if args.cast_nil == nil or args.cast_nil == true then
            return false
        else
            return
        end
    elseif t == 'boolean' then
        return value
    elseif t == 'number' then
        if value == 0 then return false end
        return true
    elseif t == 'string' then
        local tmp = string.lower(value)
        for _, v in ipairs(i18n.bool_false) do
            if v == tmp then
                return false
            end
        end
        return true
    else
        error(string.format(i18n.errors.not_a_boolean, tostring(value), t))
    end

end

function util.cast.number(value, args)
    -- Takes an arbitrary value and attempts to convert it to a number.
    --
    -- args
    --  default  for strings, if default is nil and the conversion fails, an error will be returned
    --  min  error if <min
    --  max  error if >max
    args = args or {}

    local t = type(value)
    local val

    if t == 'nil' then
        val = nil
    elseif t == 'boolean' then
        if value then
            val = 1
        else
            val = 0
        end
    elseif t == 'number' then
        val = value
    elseif t == 'string' then
        val = tonumber(value)
    end

    if val == nil then
        if args.default ~= nil then
            val = args.default
        else
            error(string.format(i18n.errors.not_a_number, tostring(value), t))
        end
    end

    if args.min ~= nil and val < args.min then
        error(string.format(i18n.errors.number_too_small, val, args.min))
    end

    if args.max ~= nil and val > args.max then
        error(string.format(i18n.errors.number_too_large, val, args.max))
    end

    return val
end

function util.cast.table(value, args)
    -- Takes an arbitrary value and attempts to convert it to a table.
    -- 
    -- args
    --  split_args  If true, create an association table (rather than an array)
    --  pattern  The pattern to split strings by. Default: ',%s*'
    --  split_args_pattern  The pattern to split keys from values by. Ignored if split_args is not true.
    --      Default: '%s*=%s*'
    --  callback  A callback function to call on each value
    args = args or {}
    local pattern = args.pattern or ',%s*'
    local split_args_pattern = args.split_args_pattern or '%s*=%s*'
    local tbl
    if type(value) == 'string' then
        if args.split_args then
            tbl = util.string.split_args(value, { sep = pattern, kvsep = split_args_pattern } )
        else
            tbl = util.string.split(value, pattern)
        end
    elseif type(value) ~= 'table' then
        tbl = {value}
    else
        tbl = value
    end
    if args.callback then
        for k, v in ipairs(tbl) do
            tbl[k] = args.callback(v)
        end
    end
    return tbl
end

function util.cast.version(value, args)
    -- Takes a string value and returns as version number
    -- If the version number is invalid an error is raised
    --
    -- args:
    --  return_type: defaults to "table"
    --   table  - Returns the version number broken down into sub versions as a table
    --   string - Returns the version number as string
    --
    if args == nil then
        args = {}
    end

    local result
    if args.return_type == 'table' or args.return_type == nil then
        result = util.string.split(value, '%.')

        if #result ~= 3 then
            error(string.format(i18n.errors.malformed_version_string, value))
        end

        result[4] = string.match(result[3], '%a+')
        result[3] = string.match(result[3], '%d+')

        for i=1,3 do
            local v = tonumber(result[i])
            if v == nil then
                error(string.format(i18n.errors.non_number_version_component, value))
            end
            result[i] = v
        end
    elseif args.return_type == 'string' then
        result = string.match(value, '%d+%.%d+%.%d+%a*')
    end

    if result == nil then
        error(string.format(i18n.errors.unrecognized_version_number, value))
    end

    return result
end

function util.cast.replace_if_match(value, args)
    -- Returns a function that returns its input unchanged, unless the string value
    -- matches the 'pattern' argument, in which case the 'replacewith' value is returned.
    if ((args == nil) or (args.pattern == nil) or (value == nil)) then
        return value
    elseif string.find(tostring(value),args.pattern) then
        return args.replacewith
    else
        return value
    end
end

-- ----------------------------------------------------------------------------
-- util.validate
-- ----------------------------------------------------------------------------

util.validate = {}
util.validate.factory = {}

function util.validate.factory.number_in_range(args)
    -- Returns a function that validates whether a number is within a range of 
    -- values. An error is thrown if the value is not a number or if it is not 
    -- within the specified range.
    args = args or {}
    args.min = args.min or -math.huge
    args.max = args.max or math.huge
    return function (value)
        if type(value) ~= 'number' then
            error(string.format(i18n.errors.not_a_number, tostring(value), type(value)))
        end
        if value < args.min or value > args.max then
            error(string.format(args.errmsg or i18n.errors.number_out_of_range, tostring(value), tostring(args.min), tostring(args.max)), args.errlvl or 2)
        end
        return value
    end
end

function util.validate.factory.string_length(args)
    -- Returns a function that validates whether a string has has the correct 
    -- length. An error is thrown if the value is not a string or if its length 
    -- restrictions are not met.
    args = args or {}
    args.min = args.min or 0
    args.max = args.max or math.huge
    return function (value)
        if type(value) ~= 'string' then
            error(string.format(i18n.errors.not_a_string, tostring(value), type(value)))
        end
        local length = mw.ustring.len(value)
        if length < args.min or length > args.max then
            error(string.format(args.errmsg or i18n.errors.string_length_incorrect, tostring(value), tostring(args.min), tostring(args.max)), args.errlvl or 2)
        end
        return value
    end
end

function util.validate.factory.in_table(args)
    -- Returns a function that validates whether a table contains a value.
    -- An error is thrown if the value is not found.
    args = args or {}
    return function (value)
        if not util.table.contains(args.tbl or {}, value) then
            error(string.format(args.errmsg or i18n.errors.value_not_in_table, tostring(value)), args.errlvl or 2)
        end
        return value
    end
end

function util.validate.factory.in_table_keys(args)
    -- Returns a function that validates whether a table has a value as one of 
    -- its keys. An error is thrown if the key does not exist.
    args = args or {}
    return function (value)
        if not util.table.has_key(args.tbl or {}, value) then
            error(string.format(args.errmsg or i18n.errors.value_not_in_table_keys, tostring(value)), args.errlvl or 2)
        end
        return value
    end
end

--
-- util.cast.factory
--

-- This section is used to generate new functions for common argument parsing tasks based on specific options
--
-- All functions return a function which accepts two arguments:
--  tpl_args - arguments from the template 
--  frame - current frame object
--
-- All factory functions accept have two arguments on creation:
--  k - the key in the tpl_args to retrive the value from
--  args - any addtional arguments (see function for details)

util.cast.factory = {}

function util.cast.factory.table(k, args)
    args = args or {}
    return function (tpl_args, frame)
        args.value = tpl_args[k]
        if args.value == nil then
            return
        end
        local value = util.table.find_in_nested_array(args)
        if value == nil then
            error(string.format(args.errmsg or i18n.errors.missing_element, k))
        end
        tpl_args[args.key_out or k] = value
    end
end

function util.cast.factory.assoc_table(k, args)
    -- Arguments:
    --
    -- tbl
    -- errmsg
    -- key_out
    return function (tpl_args, frame)
        local elements
        
        if tpl_args[k] ~= nil then
            elements = util.string.split(tpl_args[k], ',%s*')
            for _, element in ipairs(elements) do 
                if args.tbl[element] == nil then
                    error(util.html.error{msg=string.format(args.errmsg or i18n.errors.missing_element, element)})
                end
            end
            tpl_args[args.key_out or k] = elements
        end
    end
end

function util.cast.factory.number(k, args)
    args = args or {}
    return function (tpl_args, frame)
        tpl_args[args.key_out or k] = tonumber(tpl_args[k])
    end
end

function util.cast.factory.boolean(k, args)
    args = args or {}
    return function(tpl_args, frame)
        if tpl_args[k] ~= nil then
            tpl_args[args.key_out or k] = util.cast.boolean(tpl_args[k])
        end
    end
end

function util.cast.factory.percentage(k, args)
    args = args or {}
    return function (tpl_args, frame)
        local v = tonumber(tpl_args[k])
        
        if v == nil then
            return util.html.error{msg=string.format(i18n.errors.invalid_argument, k)}
        end
        
        if v < 0 or v > 100 then
            return util.html.error{msg=string.format(i18n.errors.not_a_percentage, k)}
        end
        
        tpl_args[args.key_out or k] = v
    end
end

-- ----------------------------------------------------------------------------
-- util.args
-- ----------------------------------------------------------------------------

util.args = {}

function util.args.stats(argtbl, args)
    -- in any prefix spaces should be included
    --
    -- argtbl: argument table to work with
    -- args:
    --  prefix: prefix if any
    --  property_prefix: property prefix if any
    --  subobject_prefix: subobject prefix if any
    --  properties: table of properties to add if any
    args = args or {}
    args.prefix = args.prefix or ''

    local i = 0
    local stats = {}
    repeat
        i = i + 1
        local prefix = string.format('%s%s%s_%s', args.prefix, i18n.args.stat_infix, i, '%s')
        local id = {
            id = string.format(prefix, i18n.args.stat_id),
            min = string.format(prefix, i18n.args.stat_min),
            max = string.format(prefix, i18n.args.stat_max),
            value = string.format(prefix, i18n.args.stat_value),
        }

        local value = {}
        for key, args_key in pairs(id) do
            value[key] = argtbl[args_key]
        end


        if value.id ~= nil and ((value.min ~= nil and value.max ~= nil and value.value == nil) or (value.min == nil and value.max == nil and value.value ~= nil)) then
            if value.value then
                value.value = util.cast.number(value.value)
                argtbl[id.value] = value.value
            else
                value.min = util.cast.number(value.min)
                argtbl[id.min] = value.min
                value.max = util.cast.number(value.max)
                argtbl[id.max] = value.max

                -- Also set average value
                value.avg = (value.min + value.max)/2
                argtbl[string.format('%sstat%s_avg', args.prefix, i)] = value.avg
            end
            argtbl[string.format('%sstat%s', args.prefix, i)] = value
            stats[#stats+1] = value
        elseif util.table.has_all_value(value, {'id', 'min', 'max', 'value'}, nil) then
            value = nil
        -- all other cases should be improperly set value
        else
            error(string.format(i18n.errors.improper_stat, args.prefix, i))
        end
    until value == nil

    argtbl[string.format('%sstats', args.prefix)] = stats
end

function util.args.spawn_weight_list(argtbl, args)
    args = args or {}
    args.input_argument = i18n.args.spawn_weight_prefix
    args.output_argument = 'spawn_weights'
    args.cargo_table = 'spawn_weights'
    
    util.args.weight_list(argtbl, args)
end

function util.args.generation_weight_list(argtbl, args)
    args = args or {}
    args.input_argument = i18n.args.generation_weight_prefix
    args.output_argument = 'generation_weights'
    args.cargo_table = 'generation_weights'
    
    util.args.weight_list(argtbl, args)
end

function util.args.weight_list(argtbl, args)
    -- Parses a weighted pair of lists and sets properties
    --
    -- argtbl: argument table to work with
    -- args:
    --  output_argument - if set, set arguments to this value
    --  input_argument - input prefix for parsing the arguments from the argtbl
    --  subobject_name - name of the subobject

    m_cargo = m_cargo or require('Module:Cargo')

    args = args or {}
    args.input_argument = args.input_argument or 'spawn_weight'

    local i = 0
    local id = nil
    local value = nil
    
    if args.output_argument then
        argtbl[args.output_argument] = {}
    end

    repeat
        i = i + 1
        id = {
            tag = string.format('%s%s_tag', args.input_argument, i),
            value = string.format('%s%s_value', args.input_argument, i),
        }
    
        value = {
            tag = argtbl[id.tag],
            value = argtbl[id.value],
        }
        
        if value.tag ~= nil and value.value ~= nil then
            if args.output_argument then
                argtbl[args.output_argument][i] = value
            end
            
            if args.cargo_table then
                m_cargo.store({
                    _table = args.cargo_table,
                    ordinal = i,
                    tag = value.tag,
                    weight = util.cast.number(value.value, {min=0}),
                })
            end
        elseif not (value.tag == nil and value.value == nil) then
            error(string.format(i18n.errors.invalid_weight, id.tag, id.value))
        end
    until value.tag == nil
end

function util.args.version(argtbl, args)
    -- in any prefix spaces should be included
    --
    -- argtbl: argument table to work with
    -- args:
    --  set_properties: if defined, set properties on the page
    --  variables: table of prefixes
    --  ignore_unknowns: if defined, treat a version number of '?' as if it
    --    were not present 
    --  noquery: For testing; if defined, skips the query
    --  return_ids_and_keys: For testing; on return, args.version_ids and
    --    args.versionkeys are set to the IDs and keys found
    args = args or {}
    args.variables = args.variables or {
        release = {},
        removal = {},
    }

    local version_ids={}
    local version_keys={}

    for key, data in pairs(args.variables) do
        local full_key = string.format('%s_version', key)
        if args.ignore_unknowns and (argtbl[full_key] == '?') then
            argtbl[full_key] = nil
        elseif argtbl[full_key] ~= nil then
            local value = util.cast.version(argtbl[full_key], {return_type = 'string'})
            argtbl[full_key] = value
            if value ~= nil then
                data.value = value
                if data.property ~= nil then
                    version_ids[#version_ids+1] = value
                    version_keys[value] = key
                end
            end
        end
    end

    -- no need to do a query if nothing was fetched
    if (args.noquery == nil) and (#version_ids > 0) then
        for i, id in ipairs(version_ids) do
            version_ids[i] = string.format('Versions.version="%s"', id)
        end

        local results = m_cargo.query(
            {'Versions'},
            {'release_date', 'version'},
            {
                where = table.concat(version_ids, ' OR '),
            }
        )

        if #results ~= #version_ids then
            error(string.format(i18n.too_many_versions, #results, #version_ids))
        end

        for _, row in ipairs(results) do
            local key = version_keys[row.version]
            argtbl[string.format('%s_date', key)] = row.release_date
        end
    end

    if args.return_ids_and_keys ~= nil then
        args.version_ids = version_ids
        args.version_keys = version_keys
    end
end

function util.args.from_cargo_map(args)
    m_cargo = m_cargo or require('Module:Cargo')
    return m_cargo.store_mapped_args(args)
end

function util.args.template_to_lua(str)
    --[[
    Convert templates to lua format. Simplifes debugging and creating 
    examples.
    
    Parameters
    ----------
    str : string 
        The entire template wrapped into string. Tip: Use Lua's square 
        bracket syntax for defining string literals.
       
    Returns
    -------
    out : table
        out.template - Template name.
        out.args - arguments in table format.
        out.args_to_str - arguments in readable string format.
    ]]
    local out = {}
    
    -- Get the template name:
    out.template = string.match(str, '{{(.-)%s*|')
    
    -- Remove everything but the arguments:
    str = string.gsub(str, '%s*{{.-|', '')
    str = string.gsub(str, '%s*}}%s*', '')
    
    -- Split up the arguments:
    out.args = {}
    for i, v in ipairs(util.string.split(str, '%s*|%s*')) do 
        local arg = util.string.split(v, '%s*=%s*')
        out.args[arg[1]] = arg[2]
        out.args[#out.args+1] = arg[1]
    end    
    
    -- Concate for easy copy/pasting:
    local tbl = {}
    for i, v in ipairs(out.args) do 
        tbl[#tbl+1]= string.format("%s='%s'", v, out.args[v])
    end 
    out.args_to_str = table.concat(tbl, ',\n')
    
    return out
end

-- ----------------------------------------------------------------------------
-- util.html
-- ----------------------------------------------------------------------------

util.html = {}

function util.html.abbr(text, title, options)
    -- Outputs html tag <abbr> as string or as mw.html node.
    -- 
    -- options
    --   class: class attribute
    --   output: set to mw.html to return a mw.html node instead of a string
    if not title then
        return text
    end
    options = options or {}
    local abbr = mw.html.create('abbr')
    abbr:attr('title', title)
    local class
    if type(options) == 'table' and options.class then
        class = options.class
    else
        class = options
    end
    if type(class) == 'string' then
        abbr:attr('class', class)
    end
    abbr:wikitext(text)
    if options.output == mw.html then
        return abbr
    end
    return tostring(abbr)
end

function util.html.error(args)
    -- Create an error message box
    --
    -- args
    --   msg  str  The error message
    args = args or {}
    local err = mw.html.create('strong')
        :addClass('error')
        :tag('span')
            :addClass('module-error')
            :wikitext(i18n.errors.module_error .. (args.msg or ''))
            :done()
    return tostring(err)
end

function util.html.poe_color(label, text, class)
    if text == nil or text == '' then
        return nil
    end
    local em = mw.html.create('em')
        :addClass('tc -' .. label)
        :addClass(class or '')
        :wikitext(text)
    return tostring(em)
end
util.html.poe_colour = util.html.poe_color

function util.html.tooltip(abbr, text, class)
    return string.format('<span class="hoverbox c-tooltip %s"><span class="hoverbox__activator c-tooltip__activator">%s</span><span class="hoverbox__display c-tooltip__display">%s</span></span>', class or '', abbr or '', text or '')
end

function util.html.table_cell(type)
    -- Table cells
    -- type: 'yes', 'no', 'na'
    -- Returns mw.html node
    local td = mw.html.create('td')
    td
        :attr('data-sort-value', i18n.table_cells[type].sort)
        :addClass(i18n.table_cells[type].class)
        :wikitext(i18n.table_cells[type].text)
    return td
end

function util.html.format_value(tpl_args, value, options)
    -- value: table
    --  min:
    --  max:
    -- options: table
    --  func: Function to transform the value retrieved from the database
    --  fmt: Format string (or function that returns format string) to use for the value.
    --    Default: '%s'
    --  fmt_range: Format string to use for range value.
    --    Default: '(%s-%s)'
    --  color: poe_color code to use for the value. False for no color.
    --    Default: 'value' if value is unmodified; 'mod' if modified
    --  class: Additional css class added to color tag
    --  inline: Format string to use for the output
    --  inline_color: poe_color code to use for the output. False for no color.
    --    Default: Inherits from value color
    --  inline_class: Additional css class added to inline color tag
    --  no_color: (Deprecated; use color=false instead)
    --  return_color: (Deprecated; returns both value.out and value without this)

    -- Make shallow copy to avoid modifying the original table
    local value_copy = {}
    for k, v in pairs(value) do
        value_copy[k] = v
    end
    local default_color = 'value'
    local base = {
        min = value_copy.base_min or value_copy.base,
        max = value_copy.base_max or value_copy.base,
    }
    if value_copy.min ~= base.min or value_copy.max ~= base.max then
        default_color = 'mod'
    end
    if options.color ~= false and options.no_color == nil then
        value_copy.color = options.color or default_color
    end
    if options.func then
        value_copy.min = options.func(tpl_args, value_copy.min)
        value_copy.max = options.func(tpl_args, value_copy.max)
    end
    local fmt = options.fmt or '%s'
    if type(fmt) == 'function' then -- Function that returns the format string
        fmt = fmt(tpl_args, value_copy)
    end
    if value_copy.min == value_copy.max then -- Static value
        value_copy.out = string.format(fmt, value_copy.min)
    else -- Range value
        local fmt_range = options.fmt_range or i18n.range
        value_copy.out = string.format(
            string.format(fmt_range, fmt, fmt),
            value_copy.min,
            value_copy.max
        )
    end
    local inline = options.inline
    if type(inline) == 'function' then
        inline = inline(tpl_args, value_copy)
    end
    inline = inline ~= '' and inline or nil -- TODO: Eliminate the need for this?
    local inline_color = options.inline_color
    if value_copy.color and (not inline or inline_color ~= nil) then
        value_copy.out = util.html.poe_color(value_copy.color, value_copy.out, options.class)
    end
    if inline then
        value_copy.out = string.format(inline, value_copy.out)
        if inline_color or inline_color == nil and options.color ~= false then
            inline_color = inline_color or value_copy.color or default_color
            value_copy.out = util.html.poe_color(inline_color, value_copy.out, options.inline_class)
        end
    end
    if options.return_color then
        return value_copy.out, value_copy.color
    end
    return value_copy.out, value_copy
end

function util.html.wikilink(page, text)
    if text then
        return string.format('[[%s|%s]]', page, text)
    end
    return string.format('[[%s]]', page)
end

function util.html.url_link(url, text)
    return string.format('[%s %s]', url, text)
end

-- ----------------------------------------------------------------------------
-- util.misc
-- ----------------------------------------------------------------------------

util.misc = {}

function util.misc.invoker_factory(func, options)
    -- Returns a function that can be called directly or with #invoke.
    return function (frame)
        frame = frame or {}
        local args
        if type(frame.args) == 'table' then
            -- Called via #invoke, so use getArgs().
            getArgs = getArgs or require('Module:Arguments').getArgs
            args = getArgs(frame, options)
        else
            -- Called from another module or from the debug console, so assume args 
            -- are passed in directly.
            args = frame
        end
        return func(args)
    end
end

function util.misc.is_frame(frame)
    -- the type of the frame is a table containing the functions, so check whether some of these exist
    -- should be enough to avoid collisions.
    return not(frame == nil or type(frame) ~= 'table' or (frame.argumentPairs == nil and frame.callParserFunction == nil))
end

function util.misc.get_frame(frame)
    -- OBSOLETE. Use mw.getCurrentFrame() instead.
    return mw.getCurrentFrame()
end

function util.misc.get_args_raw(frame)
    -- Simple method for getting arguments. Use this instead of Module:Arguments
    -- when the extra options provided by the latter would be overkill.
    if util.misc.is_frame(frame) then
        -- Called via {{#invoke:}}, so use the args that were passed into the 
        -- template.
        return frame.args
    end
    -- Called from another module or from the debug console, so assume args 
    -- are passed in directly.
    return frame
end

function util.misc.maybe_sandbox(module_name)
    -- Did we load or {{#invoke:}} a module sandbox?
    if module_name and package.loaded[string.format('Module:%s/sandbox', module_name)] ~= nil or string.find(mw.getCurrentFrame():getTitle(), 'sandbox', 1, true) then
        return true
    end
    return false
end

function util.misc.add_category(categories, args)
    -- categories: table of categories
    -- args: table of extra arguments
    --  namespace: id of namespace to validate against
    --  ignore_blacklist: set to non-nil to ignore the blacklist
    --  sub_page_blacklist: blacklist of subpages to use (if empty, use default)
    --  namespace_blacklist: blacklist of namespaces to use (if empty, use default)
    if type(categories) == 'string' then
        categories = {categories}
    end

    if args == nil then
        args = {}
    end

    local title = mw.title.getCurrentTitle()
    local sub_blacklist = args.sub_page_blacklist or cfg.misc.category_blacklist.sub_pages
    local ns_blacklist = args.namespace_blacklist or cfg.misc.category_blacklist.namespaces

    if args.namespace ~= nil and title.namespace ~= args.namespace then
        return ''
    end

    if args.ignore_blacklist == nil and (sub_blacklist[title.subpageText] or ns_blacklist[title.subjectNsText]) then
        return ''
    end

    local cats = {}

    for i, cat in ipairs(categories) do
        cats[i] = string.format('[[Category:%s]]', cat)
    end
    return table.concat(cats)
end

-- ----------------------------------------------------------------------------
-- util.Error
-- ----------------------------------------------------------------------------

-- Prototype error object
local Error_prototype = {
    message = i18n.errors.unspecified,
    code = 'module_error',
    issue = true, -- Whether to issue error
    level = 2,
}
Error_prototype.__index = Error_prototype

function Error_prototype:throw(force)
    if force or self.issue then
        error(self.message, self.level)
    end
    return self
end

function Error_prototype:get_html()
    return util.html.error{msg=self.message}
end

function Error_prototype:get_category(args)
    return util.misc.add_category(self.category, args)
end

function util.Error(obj)
    -- Create a new error object
    obj = obj or {}
    setmetatable(obj, Error_prototype)
    return obj
end

-- ----------------------------------------------------------------------------
-- util.string
-- ----------------------------------------------------------------------------

util.string = {}

function util.string.trim(str, charset)
    --[[
    Trims leading and trailing characters in charset from a string. 
    Charset is '%s' by default, which matches whitespace characters

    This works much like mw.text.trim, using the string library instead 
    of the ustring library. This function may return erroneous results 
    if the charset needs to be Unicode-aware.
    --]]
    charset = charset or '%s'
    str = string.gsub(str, '^[' .. charset .. ']*(.-)[' .. charset .. ']*$', '%1')
    return str
end

function util.string.strip_wikilinks(str)
    --[[
    Removes wikilinks from a string, leaving the plain text
    --]]
    str = mw.ustring.gsub(str, '%[%[:?([^%]|]+)%]%]', '%1')
    str = mw.ustring.gsub(str, '%[%[:?[^|]+|([^%]|]+)%]%]', '%1')
    return str
end

function util.string.strip_html(str)
    --[[
    Removes html tags from a string, leaving the plain text
    --]]
    str = mw.ustring.gsub(str, '<[^>]*>', '')
    return str
end

function util.string.split(str, pattern, plain)
    --[[
    Splits a string into a table
    
    This does essentially the same thing as mw.text.split, but with 
    significantly better performance. This function may return erroneous 
    results if the pattern needs to be Unicode-aware.
    
    str  String to split
    pattern  Pattern to use for splitting
    plain  If true, pattern is interpreted as a literal string
    --]]
    local out = {}
    local init = 1
    local split_start, split_end = string.find(str, pattern, init, plain)
    while split_start do
        out[#out+1] = string.sub(str, init, split_start-1)
        init = split_end+1
        split_start, split_end = string.find(str, pattern, init, plain)
    end
    out[#out+1] = string.sub(str, init)
    return out
end

function util.string.split_outer(str, pattern, outer)
    --[[
        Split a string into a table according to the pattern, ignoring 
        matching patterns inside the outer patterns.
        
        Parameters
        ----------
        str : string
            String to split.
        pattern : string
            Pattern to split on.
        outer : table of strings where #outer = 2.
            Table with 2 strings that defines the opening and closing patterns 
            to match, for example parantheses or brackets.
        
        Returns
        -------
        out : table
            table of split strings.
            
        Examples
        --------
        -- Nesting at the end:
        str = 'mods.id, CONCAT(mods.id, mods.name)'
        mw.logObject(util.split_outer(str, ',%s*', {'%(', '%)'}))
        table#1 {
          "mods.id",
          "CONCAT(mods.id, mods.name)",
        }
        
        -- Nesting in the middle:
        str = 'mods.id, CONCAT(mods.id, mods.name), mods.required_level'
        mw.logObject(util.split_outer(str, ',%s*', {'%(', '%)'}))
        table#1 {
          "mods.id",
          "CONCAT(mods.id, mods.name)",
          "mods.required_level",
        }
    ]]
    local out = {}
    local nesting_level = 0
    local i = 0
    local pttrn = '(.-)' .. '(' .. pattern .. ')'
    for v, sep in string.gmatch(str, pttrn) do
        if nesting_level == 0 then
            -- No nesting is occuring:
            out[#out+1] = v
        else
            -- Nesting is occuring:
            out[#out] = (out[math.max(#out, 1)] or '') .. v
        end
        
        -- Increase nesting level:
        if string.find(v, outer[1]) then -- Multiple matches?
            nesting_level = nesting_level + 1
        end
        if string.find(v, outer[2]) then 
            nesting_level = nesting_level - 1
        end
        
        -- Add back the separator if nesting is occuring:
        if nesting_level ~= 0 then 
            out[#out] = out[#out] .. sep
        end 
        
        -- Get the last index value:  
        i = i + #v + #sep
    end
    
    -- Complement with the last part of the string:
    if nesting_level == 0 then 
        out[#out+1] = string.sub(str, math.max(i+1, 1))
    else
        out[#out] = out[#out] .. string.sub(str, math.max(i+1, 1))
        -- TODO: Check if nesting level is zero?
    end
    return out
end

function util.string.split_args(str, args)
    -- Splits arguments string into a table
    --
    -- str: String of arguments to split
    -- args: table of extra arguments
    --  sep: separator to use (default: ,)
    --  kvsep: separator to use for key value pairs (default: =)
    local out = {}

    if args == nil then
        args = {}
    end

    args.sep = args.sep or ','
    args.kvsep = args.kvsep or '='

    if str ~= nil then
        local row
        for _, str in ipairs(util.string.split(str, args.sep)) do
            row = util.string.split(str, args.kvsep)
            if #row == 1 then
                out[#out+1] = row[1]
            elseif #row == 2 then
                out[row[1]] = row[2]
            else
                error(string.format(i18n.number_of_arguments_too_large, #row))
            end
        end
    end

    return out
end

function util.string.format(format, ...)
    --[[
    String replacement with support for numbered argument conversion 
    specifications. This is useful for i18n, as translating can sometimes 
    change the order of words around.

    The format can contain either numbered argument conversion specifications 
    (i.e., "%n$"), or unnumbered argument conversion specifications (i.e., "%"), 
    but not both.

    If numbered argument conversion specifications are not needed, consider 
    using string.format() from the Lua string library instead.

    Example:
        local format = 'Bubba ate %2$d %1$s. That\'s a lot of %1$s!'
        util.string.format(format, 'hotdogs', 26)
            -> Bubba ate 26 hotdogs. That's a lot of hotdogs!
    ]]

    local values = {}
    for v in string.gmatch(format, '%%(%d+)%$') do
        values[#values+1] = select(v, ...)
    end
    if #values == 0 then
        -- Using unnumbered argument conversion specifications, so just pass 
        -- args to string.format().
        return string.format(format, ...)
    end
    format = string.gsub(format, '%%%d+%$', '%%')
    return string.format(format, unpack(values))
end

function util.string.first_to_upper(str)
    --[[
        Converts the first letter of a string to uppercase
    --]]

    -- Reassign to variable before returning since string.gsub returns two values
    str = str:gsub('^%l', string.upper)
    return str
end

util.string.pattern = {}
function util.string.pattern.valid_var_name()
    --[[
        Get a pattern for a valid variable name.
    ]]
    return '%A?([%a_]+[%w_]*)[^%w_]?'
end

-- ----------------------------------------------------------------------------
-- util.table
-- ----------------------------------------------------------------------------

util.table = {}

function util.table.length(tbl)
    -- Get number of elements in a table. Counts both numerically indexed 
    -- elements and associative elements. Does not count nil elements.
    local count = 0
    for _ in pairs(tbl) do
        count = count + 1
    end
    return count
end
util.table.count = util.table.length

function util.table.contains(tbl, value)
    -- Checks whether a table contains a value
    for _, v in pairs(tbl) do
        if v == value then
            return true
        end
    end
    return false
end

function util.table.has_key(tbl, key)
    -- Checks whether a table has a key
    return tbl[key] ~= nil
end

function util.table.has_any_key(tbl, keys)
    -- Checks whether a table has at least one of the keys
    for _, key in ipairs(keys or {}) do
        if tbl[key] ~= nil then
            return true
        end
    end
    return false
end

function util.table.has_all_keys(tbl, keys)
    -- Checks whether a table has all of the keys
    for _, key in ipairs(keys or {}) do
        if tbl[key] == nil then
            return false
        end
    end
    return true
end

function util.table.keys(tbl)
    -- Returns the keys of a table
    local keys = {}
    for k, _ in pairs(tbl) do
        keys[#keys+1] = k
    end
    return keys
end
util.table.assoc_to_array = util.table.keys

function util.table.column(tbl, colkey, idxkey)
    --[[
    Returns the values of one column of a multi-dimensional table

    tbl  A multi-dimensional table
    colkey  The column key from the inner tables
    idxkey  If provided, the column from the inner tables to index the 
            returned values by. Default: nil
    --]]
    local col = {}
    for _, row in pairs(tbl) do
        if type(row) == 'table' and row[colkey] ~= nil then
            if idxkey ~= nil and row[idxkey] ~= nil then
                col[row[idxkey]] = row[colkey]
            else
                col[#col+1] = row[colkey]
            end
        end
    end
    return col
end

function util.table.merge(...)
    --[[
    Merges the keys and values of multiple tables into a single table. If
    the input tables share non-numerical keys, then the later values for those
    keys will overwrite the previous ones. Numerical keys are instead appended
    and renumbered, incrementing from 1.
    --]]
    local tbl = {}
    for _, t in ipairs({...}) do
        for k, v in pairs(t) do
            if type(k) == 'number' then
                table.insert(tbl, v)
            else
                tbl[k] = v
            end
        end
    end
    return tbl
end

function util.table.diff(tbl1, tbl2)
    -- Finds the difference between two tables, returning a table containing the 
    -- values in tbl1 that are not in tbl2. Indexing is ignored; only values are 
    -- compared.
    local diff = {}
    for _, k in pairs(tbl1) do
        if not util.table.contains(tbl2, k) then
            table.insert(diff, k)
        end
    end
    return diff
end

function util.table.remove_duplicates(tbl)
    -- Removes duplicate values from an array.
    local new_tbl = {}
    local exists = {}
    for _, v in ipairs(tbl) do
        if not exists[v] then
            new_tbl[#new_tbl+1] = v
            exists[v] = true
        end
    end
    return new_tbl
end

function util.table.has_all_value(tbl, keys, value)
    -- Whether all the table values with the specified keys are the specified value
    for _, k in ipairs(keys or {}) do
        if tbl[k] ~= value then
            return false
        end
    end
    return true
end

function util.table.has_one_value(tbl, keys, value)
    -- Whether one of table values with the specified keys is the specified value
    for _, k in ipairs(keys or {}) do
        if tbl[k] == value then
            return true
        end
    end
    return false
end

function util.table.find_in_nested_array(args)
    -- Iterates thoguh the given nested array and finds the given value
    --
    -- ex.
    -- data = {
    -- {a=5}, {a=6}}
    -- find_nested_array{arg=6, tbl=data, key='a'} -> 6
    -- find_nested_array(arg=10, tbl=data, key='a'} -> nil
    -- -> returns "6"

    --
    -- args: Table containing:
    --  value: value of the argument
    --  tbl: table of valid options
    --  key: key or table of key of in tbl
    --  rtrkey: if key is table, return this key instead of the value instead
    --  rtrvalue: default: true

    local rtr

    if type(args.key) == 'table' then
        for _, item in ipairs(args.tbl) do
            for _, k in ipairs(args.key) do
                if item[k] == args.value then
                    rtr = item
                    break
                end
            end
        end
    elseif args.key == nil then
        for _, item in ipairs(args.tbl) do
            if item == args.value then
                rtr = item
                break
            end
        end
    else
        for _, item in ipairs(args.tbl) do
            if item[args.key] == args.value then
                rtr = item
                break
            end
        end
    end

    if rtr == nil then
        return rtr
    end

    if args.rtrkey ~= nil then
        return rtr[args.rtrkey]
    elseif args.rtrvalue or args.rtrvalue == nil then
        return args.value
    else
        return rtr
    end
end

-- ----------------------------------------------------------------------------

return util